<template>
<div>
  <router-link tag="div" to="/" class="header-abs" v-show="showAbs">
    <div class="iconfont header-abs-back">&#xe624;</div>
  </router-link>
  <div class="header-fixed" v-show="!showAbs" :style="opacityStyle">
    景点详情
    <router-link tag="div" to="/">
      <div class="iconfont header-fixed-back">&#xe624;</div>
    </router-link>
  </div>
</div>
</template>

<script>
export default {
  name: 'DetailHeader',
  data () {
    return {
      showAbs: true,
      opacityStyle: {
        opacity: 0
      }
    }
  },
  methods: {
    handleScoll () {
      const top = document.documentElement.scrollTop
      if (top > 60) {
        let opacity = top / 140
        opacity = opacity > 1 ? 1 : opacity
        this.opacityStyle = { opacity }
        this.showAbs = false
      } else {
        this.showAbs = true
      }
    }
  },
  // 当页面显示的时候绑定
  activated () {
    window.addEventListener('scroll', this.handleScoll)
  },
  // 当页面隐藏的时候解绑
  deactivated () {
    // 因为事件被绑定在window上，如果不解除绑定，其它页面也会被绑定该事件
    window.removeEventListener('scroll', this.handleScoll)
  }
}
</script>

<style lang="stylus" scoped>
  @import '~@styles/varibles.styl';
  .header-abs
    position absolute
    left .2rem
    top .2rem
    width .8rem
    height .8rem
    border-radius .4rem
    background rgba(0, 0, 0, 0.8);
    text-align center
    line-height .8rem
    .header-abs-back
      color #ffffff
      font-size .4rem
  .header-fixed
    position fixed
    top 0
    left 0
    right 0
    height $headerHeight
    line-height $headerHeight
    text-align center
    color #fff
    background $bgColor
    font-size .32rem
    z-index 10
    .header-fixed-back
      top 0
      left 0
      position absolute
      width .64rem
      text-align center
      font-size .4rem
      color #ffffff
</style>
